Imparting crease resistance to fibrous silk structures through treatment with gaseous formaldehyde

ABSTRACT

A METHOD OF FINISHING SILK FIBROUS STRUCTURE WHICH COMPRISES TREATING THE SILK FIBROUS STRUCTURE WITH A SOLUTION CONTAINING AT LEAST ONE COMPOUND SELECTED FROM THE FOLLOWING GROUP: (A) UREA OF THIOUREA; (B) A MIXTURE OF FORMALDEHYDE-CONTAINING LOW GRADE CONDENSATION RESIN AND UREA OR THOUREA; (C) ALIPHATIC, ALICYLIC OR AROMATIC COMPOUNDS HAVING AT LEAST TWO HYDROXYL GROUPS AND HAVING MOLECULAR WEIGHT OF NO MORE THAN 400; (D) ALIPHATIC AMINES HAVING AT LEAST TWO GROUPS SELECTED FROM HYDROXYL AND AMINO AND HAVING MOLECULAR WEIGHT OF NO MORE THAN 400; DRYING THE TREATED FIBROUS STRUCTURE UNTIL THE MOISTURE CONTENT OF SAID FIBROUS STRUCTURE REACHES NO MORE THAN 10% AND THEN, TREATING SAID FIBROUS STRUCTURE WITH GASEOUS FORMALDEHYDE AT A TEMPERATURE OF NO LESS THAN 100*C. DURABLE AND HIGH CREASE-RESISTANCE IS OBTAINED WITHOUT ADVERSLY AFFECTING EXCELLENT PROPERTIES PECULIAR TO SILK FIBROUS STRUCTURE.

y 1972 YOSHITAKA suemo-ro ET AL 3, 7

IMPARTING GREASE RESISTANCE TO FIBROUS SILK STRUCTURES THROUGH TREATMENT WITH GASEOUS FORMALDEHYDE Filed Nov. 10, 1970 2 Sheets-Sheet 1 ANGULAR RECOVERY [%J (D UNTREATED RELATIVE HUMIDITY AT 20C //VV[/1/70S 70316774674 51/67/1407? 1 5/10 SAM/VOM/J A #AZ 0/1 05 A OUM/ ATTOR Y3 July 18, 1972 ANGULAR RECOVERY YOSHITAKA SUGIMOTO ETAL IMPARTING GREASE RESISTANCE T0 FIBROUS SILK STRUCTURES 7'5 RELATIVE HUMIDITY 2 Sheets-Sheet 2 ATTORN Y5 United States Patent 3,677,694 IMPARTING CREASE RESISTANCE T0 FIBROUS SILK STRUCTURES THROUGH TREATMENT WITH GASEOUS FORMALDEHYDE Yoshitaka Sugimoto and Isao Sannomiya, Hyogo-ken, and Kazunobu Noumi, Osaka, Japan, assignors to Kanegafuchi Boseki Kabnshiki Kaisha, Tokyo, Japan Filed Nov. 10, 1970, Ser. No. 88,361 Claims priority, application Japan, Nov. 10, 1969, t l/90,369; July 21, 1970, 45/63,834; July 30, 1970, 45/ 67,085

Int. Cl. D06m 3/02 US. Cl. 8127.6 6 Claims ABSTRACT OF THE DISCLOSURE A method of finishing silk fibrous structure which comprises treating the silk fibrous structure with a solution containing at least one compound selected from the following group: (a) urea of thiourea; (b) a mixture of formaldehyde-containing low grade condensation resin and urea or thiourea; (c) aliphatic, alicyclic or aromatic compounds having at least two hydroxyl groups and having molecular weight of no more than 400; (d) aliphatic amines having at least two groups selected from hydroxyl and amino and having molecular weight of no more than 400; drying the treated fibrous structure until the moisture content of said fibrous structure reaches no more than 10% and then, treating said fibrous structure with gaseous formaldehyde at a temperature of no less than 100 C. Durable and high crease-resistance is obtained without adversely affecting excellent properties peculiar to silk fibrous structure.

This invention relates to a crease-resisting finish of silk fibrous structures, and particularly to a creaseproofing method for remarkably reducing the creation of creases at the time of wearing without adversely affecting excellent properties peculiar to silk fibrous structures.

Silk fibrous structures exhibit unique hand-feeling and luster as well as excellent mechanical properties such as tensile strength, elasticity, etc. On the contrary, they have a defect, that is, they crease easily at wearing. The creation of crease is seriously afiected by relative humidity in an atmosphere surrounding the fibrous structure; it considerably increases with increase of the relative humidity. At the time of seating, creases are easily created at the seat and the waist portions of silk clothes because relative humidity of the above portions is high, i.e., usually 73 to 95%, and the resultant crease is persistent. It is very difiicult to prevent the creation of such creases.

Further, dyed silk fibrous structure is inferior in color fastness, particularly in Wet color fastness such as washing fastness and sweat fastness. Therefore, in the case where a printed article of silk fibrous material is washed at home, a part of the dyestuif comes out furiously and stains the fields of white or other colors and accordingly, coloring is changed. In the case of a dip dyed article, coloring is also changed and mottles are created due to loss of dyestulf. Still further, the creation of crease at the time of washing at home and the loss of shape are brought about. Accordingly, all of the dyed articles of silk fibrous 3,677,694 Patented July 18, 1972 ice material are obliged to be only dry-cleaned in the existing circumstances.

Heretofore, in order to prevent the creation of creaseswhich is the only defect in the silk fibrous structure, many attempts have been made. They are broadly divided into the following two categories:

(1) Liquid phase process comprising treating the fibrous structure with a solution containing, for example, isocyanates-organic acid, urea-formalin, methylol acrylamide-stannic chloride, etc. and then polymerizing the above component inside the fiber.

(2) Gaseous phase process comprising treating the fibrous structure with a vaporized monomer such as vinyl acetate, acrylonitrile or formaldehyde in the presence of a cataylst.

It may be gathered from the above processes that many of the conventional crease-proofing processes of silk fi-. brous structure originate in those of cellulosic fibrous structure. However, even if the crease-proofing process of cellulosic fibrous structure is applied to silk fibrous structure as it was applied to the former structure, good results cannot be expected because silk fiber is quite different from cellulosic fiber in hand-feeling, luster, etc. as well as their molecular structure and physical properties. For example, relating to their molecular structure, cellulose fiber has many --OH groups in its molecule and accordingly, a distance between the functional groups is relatively short. On the other hand, silk has various kinds and a small quantity of functional groups such as NH group, --OH group, -COOH group, etc. in its molecule. In other words, a small quantity of functional groups is sparsely distributed in the molecule of silk and consequently, a distance between functional groups is relatively long. Therefore, even in the case where, such attempt to produce crOss-linkings between the silk molecule by applying a liquid phase process, is made, cross-linkings between the functional groups can hardly be created and the cross-linking agents so applied are wholly hardened within gaps between the molecules or bonded to the functional groups only at their one end, that is, they are grafted onto the functional groups. The reason for the above is that the extreme length limit of polymerized cross-linking agent does not extend beyond the distance between the functional groups in silk molecule. Accordingly, good results can hardly be expected from the conventional processes as applied to cellulose fibrous structure. In order to satisfactorily effect the crease-proofing, very large amounts of cross-linking agent are needed and the fibrous structure loses its own characteristics such as excellent hand-feeling. Consequently, silk clothes having both durable crease-resisting property and their own characteristics is not obtainable. Further, crease-resistance may also be achieved by covering fibrous material with the polymerized resin from the cross-linking agent or by filling up the gaps between molecules with the resin, besides by cross-linking molecules as described above, or by the combination of cross-linking, covering and filling-up. However, the covering layer of the polymerized resin from, for example, isocyanates-organic acid etc. can hardly prevent the creation of creases originating from microscopic structure within the molecule and adversely affects hand-feeling and luster. In short, a liquid phase process is not industrially practicable because sufiicient cross-linkings cannot be produced and additionally covering or filling-up of polymerized resins does not create satisfactory crease-resistance and damages silks own characteristic such as hand-feeling and luster.

Additionally, in the case of employing a gaseous phase process using vaporized monomer, the conversion of the monomer is low because the polymerization is a reversible reaction and accordingly, sufiicient cross-linkings between the molecules is not obtainable, resulting in poor creaseresistance. For example, crease resistance achieved by the conventional gaseous phase crease-proofing process using acrylonitrile is shown in Table 1 in comparison with that achieved by the method of the present invention.

TABLE 1 Treating conditions: 1 Crease resistance lUntreated 50.0 Vapor phase acrylonitrile-treated (at 30 C.

for hrs.) 75.0 Invention (after treating with thiourea zinc nitrate 1%, treating with formaldehyde at 120 C. for 3 hrs.) 97.24 Invention (after treating with thiourea 10%- lower trimethylol-melamine condensation product '3%-zinc nitrate 3%, treating formaldehyde at 120 C. for 3 hrs.) 95.7

I 1 Testing method is as follows: each specimen is cut 4 cm. by 1 cm. along the warp and weft, respectively, and left at RH 65% for a period of one night. The strip is then folded in half so that it measures 2 cm. by 1 cm. and weighted with 2 kg. for a period of 5 min., after which it is removed. Then the strip is suspended on a strained wire for 3 min. The distance (a mm.) between the extremities is measured. (11.:5 times.) The crease-resistance may be calculated from the following formula and expressed as a percentage Grease resistance X 100 Further, a liquid and gaseous phase-2 stage process for cellulose fibrous structure, i.e., a compromised process between the above two processes is disclosed in Japanese patent publication Sho. 374596. The process comprises lipping the fibrous structure with an aqueous solution of oxy acid salt of melamine and thereafter, treating the same with vaporized formaldehyde in the presence of water. However, in the case where the process is applied to silk fibrous structure, the resultant fibrous structure develops the similar defects to those described above; roughening and hardening of the hand-feeling, reduction of luster and discoloration are caused and therefore, satisfactory results cannot be obtained.

Further, as described before, dyed or printed silk fibrous structure is inferior in wet fastness such as washing fastness and sweat fastness. The reason for the above is presumed that, while polymerized resin is usually produced as a surface layer 'over the fibrous material and internally in gaps between the molecules by the conventional creaseresisting finish, the internal production of polymerized resin is insufficient in the case of taking care that the excellent hand-feeling is not lost and accordingly, bonds due to van der Waals force and hydrogen bond between the polymerized resin and dyestuff molecule penetrated into the fibrous material are not fully formed.

An object of the present invention is to provide a creaseresisting finish for silk fibrous structure whereby the fibrous structure is given durable and high crease-resistance and it maintains its own characteristics such as handfeeling, luster, etc. as well as its own physical properties such as tenacity, elongation, etc.

Another object of the present invention is to provide a wash-and-wear finish for silk fibrous structure, particularly dyed or printed silk fibrous structure whereby the fibrous structure is given excellent color fastness.

Other objects and advantages will become apparent from the following description.

According to the present invention, a finishing process for a silk fibrous structure which comprises treating the silk fibrous structure with a solution containing at least one member selected from the group consisting of (a) Urea or thiourea,

(b) A mixture of formaldehyde-containing low condensation resin and urea or thiourea,

(c) Aliphatic, alicyclic or aromatic compounds having at least two hydroxyl groups and having molecular weight of no more than 400,

(d) Aliphatic amines having at least two groups selected from hydroxyl and amino and having molecular weight of no more than 400, drying the treated fibrous structure until the moisture content of the fibrous structure reaches no more than. 10% and thereafter, treating the resultant fibrous structure with gaseous formaldehyde at a temperature of no less than |l00 C., is provided. It should be noted, in the practice of the present invention, that moisture content of the silk fibrous structure to be treated with gaseous formaldehyde is no more than 10% by weight preferablyno more than 7% by weight, and a temperature of formaldehyde vapor is no less than C., preferably no less than C.

Formaldehyde-containing low grade condensational resin, which is used together with urea or thiourea in the process of the present invention, includes urea resins such as methylolurea, methylol ethylene urea, methylolthiourea, methylol ethylene thiourea, methylol propylene urea and methylol propylene thiourea, etc.; glyoxal resins such as dimethylol glyoxal nonurein, tetramethylol glyoxal diurein, etc.; melamine resins such as trimethylolmelamine and hexamethylolmelamine, etc.; urone resins such as dimethylol urone, etc.; triazine resins such as triethyleneiminotriazine, etc.; triazone resins such as dimethyloltriazone, etc.; and methylol acrylamide. They may be used alone or in combination.

Formaldehyde-containing low grade condensational resin can be present in the mixture in a wide range of concentrations such as, for example, at a resin-to-urea or thiourea ratio of from 1:9 to 9:1 and preferably in the range from 3:7 to 7:3. In the case where the resin-tourea or thiourea ratio is less than 1:9, the object of addition of the condensational resin is not attainable. In the case where the ratio is more than 9:1, high crease-resistance is not obtainable.

Typical aliphatic compounds having at least two hydroxyl groups and having molecular weight of no more than 400, whichare used in the present invention, are ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, triethylene glycol, 1,2,6-hexanetriol, tartaric acid, glycerine and mannitol, etc. Typical alicyclic compounds are cycloheXane-1,3-diol, cyclohexane-l,4-diol, cyclohexane-l,2,3-triol, etc. Typical aromatic compounds are 2,5-dioxybenzoic acid, 2,4-dioxybenzoic acid, 1,2-dioxybenzoic acid, 4,6-dioxy-O-toluylic acid, 3,5- dioxytoluene, 3,5-dioxypropyl benzene, etc.

Typical aliphatic amines having at least two groups selected from hydroxyl and amino and having molecular weight of no more than 400 are ethanolamine, ethylenediamene, trimethylenediamene, tetramethylenediamine, pentamethylenediamine, hexamethylenediamene, heptamcthylencdiamene and octamethylenediamene, etc.

These compounds, when they have high molecular weight, can hardly permeate themselves into the fibrous material and they are mostly stuck in the surface layer of the fiber. Accordingly, when the resultant fibrous material is treated with formaldehyde vapor, condensational resin grade is produced not only inside the fiber but, for the most part, on the surface of the fiber, resulting in deteriorated handfeeling. The resultant fiber appears as though it has been coated with the resin and high crease-resistance cannot be obtained. A preferred average molecular weight is no more than 100 for the aliphatic and alicyclie hydroxy compound, no more than 150 for the aromatic hydroxy compound and no more than 100 for the aliphatic amine.

Among the above-listed compounds, ethylene glycol as aliphatic hydroxy compound, cyclohexane-1,3-diol as alicyclic hydroxy compound, 2,5-dioxybenzoic acid as aromatic hydroxy compound and ethanol amine as aliphatic amine are most preferable.

These compounds may be used alone or in combination. These compounds or mixtures are dissolved in water or organic solvent such as methanol, ethanol, etc. A preferred concentration range of the compound or mixture in solution is from 1 to 30% by weight, particularly from 5 to 25% by weight. If desired, polymerizationpromoting catalyst may be added to the solution.

The solution is applied to silk fibrous structure by conventional method such as padding, spraying and dipping, etc. and, if desired, squeezed by, for example, a mangle so that an adhered amount of the compound or mixture is from 2.5 to 25% OWF and preferably from 5 to 15% OWF. In the case where the amount is less than 2.5% OWF, suflicient cross-links cannot be formed. On the contrary, an amount of more than 25 OWF results in a coarse and hard hand-feeling.

,As catalysts, which are used in the present invention, for example, inorganic ammonium salts such as ammonium chloride, ammonium nitrate, ammonium sulfate, etc.; inorganic metal salts such as magnesium chloride and zinc nitrate, etc.; organic acids such as tartaric acid, etc. and organic amines such as 2-amino-2-methylpropanol hydrochloride, etc. are enumerated.

A preferred amount of catalyst varies depending upon the particular catalyst, temperature of gaseous formaldehyde and reaction period, etc. and it is in the range from 0.5 to 30% based on the weight of the above-said compound or mixture. In the case where the amount is less than 0.5%, the desired object is not attainable. On the other hand, in the case of more than 30%, reaction rate is not so improved and degree of polycondensation is reduced due to degradation.

Silk fibrous structure having picked up the above compound, is then dried until the moisture content of the fibrous structure reaches no more than by weight and is successively treated with gaseous formaldehyde at a temperature of no less than 100 C. Drying may be effected by heating, air-drying or any other drying means. Drying should be made as fully as possible, i.e. until the moisture content reaches no more than 10% and preferably no more than 7%, so that the trouble due to moisture will not arise in the gaseous phase reaction process. In this connection, if moisture exceeding 10% exists in the silk fibrous structure during the reaction, handfeeling of the structure is made coarse and hard. Gaseous formaldehyde may be produced, for example, by heating paraformaldehyde or by adding concentrated sulfuric acid to trioxane. As other convenient source of gaseous formaldehyde, for example, low grade polyoxymethylene glycol, a-polyoxymethylene, fi-polyoxymethylene, polyoxymethylene glycol derivatives and 'y-polyoxymethylene are enumerated.

In case a temperature of gaseous formaldehyde is less than 100 C., satisfactory high crease resistance is not obtainable, which is apparent from FIG. 1 showing relationships between crease resistance (expressed as angular recovery), relative humidity and temperature at gaseous formaldehyde treatment. Therefore, temperature should be no less than 100 C. and preferably no less than 120 C. In the case of high temperature exceeding 180 C.,

troubles such as coloration, fragility and hardening of hand-feeling are arisen at times. But, if air existing inside a treating chamber is completely replaced with inert gas such as nitrogen gas and then gaseous formaldehyde is fed into the chamber, such troubles are corrected even at a high temperature exceeding 200 C. In the case of using a solid source of gaseous formaldehyde such as paraformaldehyde powder, concentration of gaseous formaldehyde may be easily regulated by adjusting pressure hesides temperature.

Suitable treating conditions such as concentration of formaldehyde, temperature, pressure, period and impurities contained in gaseous formaldehyde, etc. vary depending upon the particular compound reacted with formaldehyde, the particular catalyst, etc. Therefore, it is difiicult to stably maintain formaldehyde monomer during the reaction, because formaldehyde monomer is easily changed to polymer. The resulting formaldehyde polymer is deposited on the surface of the fibrous structure and form: protective coatings, which prevent the penetration of formaldehyde monomer into the inner part of the fibrous structure. Accordingly, resin-formation is effected only on the surface of the fibrous structure, both which and the deposition of formaldehyde polymer result in deterioration of hand-feeling and brittleness of the resultant fabric. The polymer coatings easily come out of the fiber at laundering or at washing after finishing, resulting in deterioration of crease resistance.

Therefore, in the practice of the treatment with gaseous formaldehyde, it is preferred. that gaseous formaldehyde is maintained at a temperature higher than the equilibrium condensation temperature determined depending upon the particular pressure so that gaseous formaldehyde is not transformed into polymer during the reaction. By the term equilibrium condensation temperature is meant the upper limit of a temperature range at which gaseous formaldehyde monomer or its low molecular weight polymer can be transformed into solid polymer under the particular pressure. By low molecular weight polymer is meant that of gaseous, for example, trioxane, tetraoxane land the like.

The method of treating the fabric with gaseous formaldehyde will be more concretely described below.

Gaseous formaldehyde, which is produced by heating a convenient formaldehyde source, for example, formaldehyde polymer such as paraformaldehyde, trioxane, etc. or formalin containing 30 to 40% of formaldehyde, is fed through a feeding pipe into a treating chamber. The pipe and the chamber are heated at a temperature higher than the equilibrium condensation tempreature, and preferably, gaseous formaldehyde is additionally heated at a temperature higher than the equilibrium condensation temperature by a superheater so that the formaldehyde polymer formation is eifectively prevented and formaldehyde polymer contained in gaseous formaldehyde is decomposed to form monomer.

In order that temperature of gaseous formaldehyde does not fall lower than the equilibrium condensation temperature at its contacting point with fabric owing to heat absorption by the fabric and endothermic reaction, the fabric is previously heated or internal pressure of the chamber is previously reduced to less than the equilibrium condensation pressure and the amount of gaseous formaldehyde flowing into the chamber is regulated so that the internal pressure of the chamber does not exceed the equilibrium condensation pressure. The term equilibrium condensation pressure is meant by the lower limit of a pressure range at which gaseous formaldehyde monomer or its low molecular weight polymer can be transformed into solid polymer under the particular temperature.

In order to effect uniform polycondensation, gaseous formaldehyde monomer should be penetrated into the fibrous structure, which is attainable by replacing air existing at the inner part of the fibrous structure with formaldehyde. Accordingly, gaseous formaldehyde is forced to penetrate the fabric in one direction by creating the difference of pressure or the partial pressure of air surrounding and existing inside the fibrous structure is previously reduced to no more than 150 mm. Hg and preferably no more than 60 mm. Hg by sucking out air by a vacuum pump and thereafter, formaldehyde is fed into the chamber. If silk fabric is left in the chamber at a temperature of more than 100 C. in the presence of air for 1 to 5 hours, troubles such as hardening of hand-feeling, brittleness of the fiber and and fading arise. However, such troubles do not arise at a reduced partial pressure of no more than 150 mm. Hg. From the above viewpoint, it

is preferred that air existing at the inner part of the fibrous structure is replaced with formaldehyde or air surrounding and existing inside the fibrous structure is sucked out by a vacuum pump before or at the beginning of treatment.

Further, it should be noted that, in the case where the silk fabric containing a reactive compound with formaldehyde is treated with gaseous formaldehyde which contains a proper quantity of steam, excellent hand-feeling and gloss of the silk fiber do not deteriorate in the least through the treatment. Polycondensation of formaldehyde and the reactive compound is effected at two stages; first, addition reaction occurs to form an intermediate and secondly, polycondensation occurs through dehydration to form a polycondensation resin. And, it is presumed that, when partial pressure of steam is no less than ,5 preferably within a range of to of that of gaseous formaldehyde, addition reaction is uniformly effected all over the fabric and thereafter, polycondensation is promoted by dehydration, and hence resin is uniformly formed all over the fabric.

f5 order to prevent the condensation of steam, temperatures of the chamber, the fabric and the feed pipe must be kept at higher than the saturated vapor temperature determined depending upon the particular partial pressure, which is similar to the case of gaseous formaldehyde, as described above.

As described before, in the case where the fibrous structure having a moisture content exceeding is treated with gaseous formaldehyde, satisfactory results cannot be expected. Therefore, the partial pressure of steam and temperature should be regulated so that the moisture content is maintained at no more than 10% and preferably no more than 7% during gaseous phase treatment.

Characteristic features of the present invention will be more fully described below.

According to the present invention, it is presumed that cross-linking between functional groups in silk fiber molecule and filling up effect of resin, which heretofore could not be expected, are properly achieved. That is, polycondensation of the compound such as urea or thiourea with formaldehyde occurs at solid-gaseous phase and the resultant product reacts on functional groups in silk fiber and hence, a cross-link between the functional groups is formed. Additionally, the condensation product fills in the fibrous structure. Consequently, it is presumed that cross-linking and filling up go hand-in-hand to achieve high crease resistance. The silk fabric, which has been treated by the method of the present invention, exhibits remarkably improved crease-resisting property even at a high humidity.

Further, contrary to the fact that hand-feeling and drapery of silk fabric are deteriorated through the conventional crease-resisting finish, the method of the present invention does not adversely affect hand-feeling and drapery of silk fabric in the least and achieves a weighting effect of approximately resulting in dignified silk fabric.

Still further, contrary to the fact that mechanical properties such as tear strength are also deteriorated through the conventional crease-resisting finish of cotton or other fibrous structure, mechanical properties of the silk fabric of the present invention are rather improved as compared with those of untreated silk fabric. Moreover, the crease-resisting finish of the presentinvention does not cause any troubles in dyeing and other aftertreating processes.

It should be noted that the crease-resisting finish using low grade formaldehyde condensational resin together with urea or thiourea superior to the finish only using urea or thiourea. Because the former finish does not make silk fabric opaque in the least and crease resistance of the resulting fabric does not deteriorate.

In accordance with our research wherein a scanning type electron microscope is used, fibers of the fabric immediately after being treated with urea or thiourea and gaseous formaldehyde, have fine and smooth surface similar to those of untreated fabric even though the former fabric has a high weighting of approximately 20%. This fact shows that both urea or thiourea molecule and formaldehyde molecule deeply disperse inside the fiber and form resin therein. However, in the case where the'fabric is subjected to steaming at a temperature of more than C. or it is dipped in a hot water bath of more than 70 C. for a long period after being treated with gaseous formaldehyde, a large quantity of resin is deposited on the surface, resulting in the deterioration of crease resistance and the loss of transparency, because the resin, which has been deposited inside the fiber and which has not been reacted with silk fibroin, migrates to the surface by steaming or hot water treatment.

On the other hand, such migration cannot be observed in the fabric having been treated with a mixture of urea or thiourea and formaldehyde condensational resin even in the case where it is subjected tosteaming or to hotwater treatment after crease-resisting finish. The reason for the above is as follows. When silk fiber is dipped in a solution containing the mixture, urea or thiourea deeply penetrates and disperses into the fiber, but low grade resin does not deeply disperse and stays on the surface. And, when gaseous formaldehyde is applied, urea or thiourea forms relatively low grade resin at the inner part of the fiber, but, the above-said low grade resin staying on the surface increase still more to form a water-insoluble and relatively high molecular weight resin. Because the low grade resin staying on the surface is directly heated in the presence of a catalyst. Thus, a protective layer of the water-insoluble resin prevents migration of the relatively low grade resin.

Next, it should be also noted that the crease-resisting finish using a single compound or mixture selected from aliphatic hydroxy compounds, amines and aromatic hydroxy compounds, or a mixture of the above compound and urea or thiourea provides the fabric which is particularly excellent in crease resistance to washing and colorfastness to washing. In fact, as apparent from the examples, reduction of wet crease resistance and fading of the fabric was scarcely recognized even after repeated launderings of 20 times. According to the above method, it is presumed that formation of cross-link between functional groups in silk molecule and filling up of waterinsoluble resin are effectively obtained. Thus, the method provides a practical wash-and-wear finish.

By silk fibrous structure is meant not only the fibrous structure wholly composed of silk fiber, but also yarns or threads, woven fabric, knitted fabric and cords or strings prepared by mix spinning or mix weaving from silk fiber and other natural or man-made fibers.

Following examples are given in order that the invention may be more fully understood. Crease-resistance,

gloss, whiteness degree and wash-and-wear characteristic are determined by the following methods:

(1) Crease resistance Crease resistance is determined by measuring the angular recovery as directed in JIS-L1041-(c) method. Procedure is as follows: Fabric is out 1.5 cm. by 4 cm. to obtain a specimen strips. The strip is inserted between two superimposed metal leaves of the holder of Monsantotype tester, and an exposed end of the specimen is lifted over and back on the shorter metal leaf. The holder and specimen are inserted in a press holder, on which a load of 500 g. is applied. After min., the load is removed and the exposed end of the specimen holder is carefully inserted in the mount on the face of the tester. Care is taken so as not to roll the exposed end of the specimen, and the specimen holder is aligned properly on the mounting shelf. In order to eliminate gravitational effects, the

dangling specimen leg is .kept aligned with the vertical guide line during the 5 min. recovery period. Angle of the specimen in degrees is measured and angular recovery is calculated from the following equation:

Angle in degrees Angular recovery (percent) An average value for the warp and filling directions, each being 5 times, is calculated. Before the above determinations, the specimen is conditioned at a relative humidity of 65%, 85%, 90% and 95% and a temperature of 20 C. for to hours.

(2) Gloss Gloss is determined by observation with the naked eye of ten persons. Results are expressed by the following five indications:

: extremely superior superior common inferior extremely inferior (3) Whiteness degree Whiteness degree is determined using photoelectric spectrophotometer EPU-2Atype (made by Hitachi, Japan). The whiteness is expressed by a percentage in comparison with whiteness of the scoured silk fabric at 440 III/1., the latter whiteness degree being 100% as standard for comparison.

(4) Wash-and-wear characteristics the silk Habutai is laundered ten or twenty times under the following conditions: Washing machine, Toshiba VH- 45 type (made by Toshiba-Electric, Japan; a jetstream type, slow revolution); laundering, in 0.5% Monogen (Neutral detergent, made by Daiichi Kogyo Seiyaku, Japan) aqueous solution at 40 C. for 15 min; Washing, for 10 min.

Test specimen is Wetted by the method as directed in JIS-L1076-5.22.1-(2) and then, test is made by the method of JIS-L1076-5.22.2-(B). Crease-resistance is calculated by the method of JIS-L107 65.22.3. The crease resistance is referred to as wet crease resistance in the specification.

EXAMPLE 1 Scoured silk Habutai (plain weave fabric prepared from silk filament yarn) was dipped in an aqueous bath containing 10% of thiourea and 1% of zinc nitrate as catalyst at room temperature and then squeezed to a pick-up of 100%. After it was dried so that the fabric had a moisture content of 6% it was placed in a closed chamber filled with gaseous formaldehyde at a temperature of 0., 100 C. and 120 C., evolved from paraformaldehyde.

The method by which the formaldehyde was applied will be more fully described below.

The dried fabric was placed in a closed chamber and heated to 80 C. to 120 C. Then, air existing inside the chamber was sucked out by a vacuum pump so that internal air pressure was reduced to less than 150 mm. Hg and thereafter, a mixed gas of formaldehyde and steam was fed into the vessel until the internal pressure reached 0.5 to 1.2 kg./cm. abs. A ratio of the partial pressure of steam-to-that of formaldehyde was to /2. A gaseous formaldehyde-evolving apparatus, a gas-feeding pipe and the above chamber were maintained at a temperature of no less than 120 C. so that formaldehyde did not polymerize at the applied pressure, i.e., 0.5 to 1.2 kg./cm. abs. The fabric was maintained at the above temperature and pressure for a period of 30 min. to 3 hours.

Crease-resisting properties of the resultant fabrics are shown in FIG. 1. As apparent from FIG. 1, there exists a close relationship between crease-resisting property (indicated as angular recovery in percent) and relative humidity, that is, creaseresistance proportionally increases with increase of the temperature of gaseous formaldehyde and there is a critical point in a temperature range between 80 C. and 100 C. Further, there is a large difference of angular recovery in a relative humidity range exceeding which corresponds to the relative humidity in atmosphere of the seat and waist portions of clothes.

In other words, in the case of the silk fabric having been treated with formaldehyde at a temperature of 100 C. or 120 *C., crease-resistance depends upon relative humidity only to a slight degree and the angular recoveryrelative humidity curve is nearly horizontal. On the other hand, in the case of the fabric having been treated at a temperature of 80 C., angular recovery describes a sharply downward curve in relative humidity ranges exceeding 80% and falls to approximately 60% at a relative humidity of which shows that: the fabric is not fit for practical use and accordingly, gaseous formaldehyde should be applied at a high temperature, i.e., no less than C.

EXAMPLE 2 Scoured Fuji silk (plain weave fabric prepared from silk spun yarn) and scoured silk Habutai were dipped in a mixed bath of an aqueous solution containing thiourea and an aqueous solution containing thiourea and a catalyst at room temperature and then squeezed to a pick up of 100%. After the fabrics were dried with hot air so that they had a moisture content of 5%, they were treated with gaseous formaldehyde vaporized from paraformaldehyde in the similar manner to those described in Example 1. After soaping, rinsing and drying, the fabrics were tested. Results are given in Table 2.

TABLE 2 Monsanto crease-resistance Degree of dye absorp- Pre-treatment Gasteoustphaste (angularrecoveryin percent) tion (percent WF,)

rea men Specimen Period Temp. C.)/ RH RH RH RH RH No. fabrics Bath composition (min) period (hr.) 65% 75% 85% 95% 100% Untreated Treated 511k Habutai-- 30 1110 1 90.0 90.1 90.0 88.0 87.5 0.7 2.0

30 135/3 89.5 89.5 89.5 89.0 87.2 0.6 1.9 g 30 135/3 88.0 87.0 87.0 86.5 86.0 0.0 2.0 F ink g fn 2 el l l 1 7 57 120/3 88.0 87.5 87.0 86.0 86.0 0.7 1.8 8 u' s ourea -amino--me ypropano 1 Hydrochloride 1% 30 113/4 87.0 87.0 87.0 9 Thiourea, 10% 135/3 87.5 87.5 87.0 10 Conventionalmethod 85.0 82.0 75.0 11 Shirt 89.5 89.0 89.0 12.--" Silk Habutai 79.0 78.5 74.0 13---" Fujisilk 76.0 78.0 71.0

l Degree of dye absorption: Both untreated and treated fabrics were dyed 1% one and the same bath and thereafter, dye was extracted from the fa r cs.

Dyestufl: Kiton Fast Orange G (Ciba) 3% 011300011: 0.5%

Bath ratio: 1:30

Temp. and period: 100 0., 1 hr.

9 Wring once.

I Wring twice.

4 Conventional method is as follows: Fuji silk was padded with a solu As apparent from Table 2, crease-resistance of the untreated fabric depends upon humidity to a. great degree and extensively drops at high humidity. Conventional fabric having been treated with urea-formaldehyde low grade condensational product also exhibits the similar behavior as the above. But, it has been proved that the fabric, which was treated by the method of the present invention, has remarkably high crease-resistance exceeding that of commercially available crease-resisting finished shirt woven from blended yarn of polyethylene terephthalate fiber and cotton. Further, the fabric exhibits such high crease-resistance and dye absorption even in a high humidity range of 85% to 95% as could not heretofore be expected.

FIG. 2 shows relationship between angular recovery and relative humidity, both data of which are listed in Table 2. In FIG. 2, reference marks (A), (B), (C) and (D) designate silk Habutai having been treated by the method of the present invention (No. 4), commercially available polyester/ cotton blended crease-resisting finished shirt (No. 11), Fuji silk having been treated by the conventional method (No. 10) and untreated silk Habutai (No. 12) respectively.

tion containing 20% of dimethylol eth lene thiourea, 3% of catalyst ACX (made by Sumitomo Chemical, Japan and 2% of quaternary pyridinium salt (trademark Neobrotex PV 100, made by Nikka Chemical, Japan) and squeezed to a pick up of 100%. After the fabric was predried at a temperature of 80 C. for 5 min., it was heated at a temperature of 145 C. for 5 min. so that the thiourea was oondensated to form resin. Then the resultant fabric was sub1ected to soaping, rinsing and drying. The above method is referred to as conventional method in Examples 2 to 5.

5 Commercially available crease-resisting finished shirt woven from blended yarn of polyethylene therephthalate fiber and cotton:

Physical properties of the above fabric designated as No. 4 are given in Table 3.

As is apparent from Table 3, contrary to the fact that tear strength of the conventional cotton fabric decreases in case it is subjected to treating with gaseous formaldehyde, tear strength and tensile strength of the fabric of the present invention are remarkably improved. Moreover, in the latter fabric, a weighting of 22% is observed and excellent hand-feeling, luster and drapery are not lost in the least.

EXAMPLE 3 The method described in Example 1 was repeated except using urea in place of thiourea of Example 1. Results are given in Table 4.

TABLE 4 Gaseous Monsanto crease-resistance Degree of dye absorp- Pre-treatment t tfiliaste (angularrecoveryinpercent) tion (percent OWF) rea en Bath Period Temp. 0.)] RH RH RE RE RE Specimeniabrics composition (min) perlod(hr.) Untreated Treated Urea g 30 135/2 89.0 89.1 89.0 86.5 80.0 0.0 2.0

1'63. Sm: Habutai" 135/3 89.0 89.0 88.0 86.0 81.0 0.7 1.8

rea Org amine Sam 30 /5 88.0 88.0 87.0 86.1 81.2 0.0 1.8 Urea 30 2150/1 89.0 89.0 88.1 80.1 80.0 0.7 1.9 Urea-" 30 150/1 88.0 88.0 87.6 86.0 80.0 0.6 2.1 Fuji silk g;; so /3 87.7 87.7 87.5 86.2 79.7 0.8 1.8 0105113701-": a0 120 5 29.2 2. Untreated silk Habutai.-. 8. Untreated Fuji silk- 76.0 75.0 71.0 63.0 Fujisilk Convegltonal 85.0 80.0 75.1 66.7

m 0 11 Commercially available TIC blended 89.5 80.0 89.0 88.0

crease-resisting finished fabric.

1 Wrlng twice:

13 As apparent from Table 4, in the case of using urea as pre-treating bath component, similar results to those obtained by using thiourea are given.

EXAMPLE 4 Silk/wool sharkskin was dipped in an aqueous bath containing 5% of thiourea and 0.5% of calcium nitrate at room temperature for a period of 30 min. and then squeezed to a pick up of 100%. After the fabric was dried with hot air so that it had a moisture content of 6%, it was placed in a chamber filled with gaseous formaldehyde vaporized by heating paraformaldehyde at a temperature of 120 C.

The method by which formaldehyde was applied was as follows:

The dried fabric was placed in the closed chamber. The chamber was heated to a temperature of 130 C. and the fabric was heated to a temperature of 80 C. by stirring and circulating hot air. After it was stopped, to stir and circulate hot air, air existing inside the chamber was sucked out by a vacuum pump so that internal air pressure was reduced to 150 mm. Hg. Thereafter, a mixed gas of formaldehyde and steam was fed through a feeding pipe heated at a temperature of 120 C. into the chamber. A ratio of the partial pressure of steam-to-that of formaldehyde was /2. A temperature of the fabric in the chamber was measured and a feeding amount of steam was so controlled that internal pressure of the chamber did not exceed the pressure of gaseous formaldehyde corresponding to that at the treating temperature. A temperature of the fabric in the chamber was raised by conductive heat and radiant heat from the inside wall of the chamber and by heat of the mixed gas of steam and formaldehyde fed into the chamber. Internal pressure of the chamber was increased to 1.0 kg./cm. while a feeding amount of the mixed gas was controlled according to the rise of temperature as described above, and thereafter, the internal pressure was maintained at 1.0 kg./cm. abs.: 0.1 kg./cm. for a period of two hours while a feeding amount of gaseous formaldehyde was controlled at two positions according to the internal pressure of the chamber. Then, the mixed gas inside the chamber was sucked out and discharged by a vacuum pump from the chamber until the internal pressure reached less than 160 mm. Hg and then, air was introduced into the chamber whereby the internal pressure rose to atmospheric pressure. After the treated fabric was taken out of the chamber, it was cooled to room temperature, rinsed with water at 15 C. to 25 C. and then subjected to steam-milling at a temperature of 103 C. for 5 min. Test results of the fabric are given in Table 5.

TABLE 5 Monsanto crease-resistance (angular recovery in percent) RH RH RH RH RH 65% 76% 85% 95% 100% Untreated 89. 88. 0 82. 1 71. 0 60. 2 Treated 90. 1 90. 0 88. 0 86. 7 80. 3

As shown in Table 5, in the case of silk/wool sharkskin, good results similar to those in silk Habutai and Fuji silk are obtainable.

EXAMPLE 5 of the silk fabric reached less than 5% immediately placed in a chamber filled with gaseous formaldehyde at a temperature of 150 C., which was produced from trioxane and cone. H S0 and did not contain moisture. After five minutes, the fabric was taken out of the chamber and cooled. Then, it was subjected to soaping and rinsing. Crease-resistance of the resultant fabric is shown in Table 6 in comparison with those of the untreated fabric and the fabric treated by the conventional method.

TABLE 6 Monsanto crease-resistance (angular recovery in percent) RH RH RH RH 75% 78. 5 74. 0 66. 0 44. 0 89. 1 89. 0 87. 1 85. 0 Treated by the conven nal method 85. 0 80. 0 75. 1 66. 7 50. 0

As to the secured but untreated silk Habutai and the treated fabric of the present invention, whiteness was determined before and after exposure to sun light. Results are given in Table 7.

degree through exposure to sun light as compared with that of the untreated fabric.

Further, tensile strength of the two fabrics was determined before and after exposure to sun light. Results are given in Table 8.

TABLE 8 Untreated, Treated, kg. kg.

Before exposure to sun light 41. 4 46. 1 After exposure for 10 days 21. 0 40. 6 After exposure for 30 days Impossible 30. 3

It is also apparent from Table 8 that reduction of tensile strength of the treated fabric is far less than that of the untreated fabric.

EXAMPLE 6 Scoured silk twill Habutai was dipped in a solution containing trimethylolmelamine low grade condensation product (trademark Sumitex resin M-3, made by Sumitomo Chemical, Japan), thiourea and 3% by weight of zinc nitrate catalyst (trademark Sumitex Accelerator KX, made by Sumitomo Chemical, Japan) and then, squeezed to a pick up of 170% with a mangle made of silicone rubber. After the fabric was dried at a temperature of 100 C. for 5 min. it was placed in a test tube, at the bottom portion of which paraformaldehyde was stuffed. The fabric was treated with gaseous formaldehyde for 3 hours which was evolved by heating the paraformaldehyde at a temperature of C. Crease resistance of the resultant fabric is given in Table 9.

TABLE 9 Crease resistance Crease resistance (after finishing) (after steaming) Gloss (percent) (percent) (after Sumitex Resin Thiourea steam- M-3 (percent) (percent) 65% RH 95% RH 65% RH 95% RH ing) As apparent from Table 9, the effect of the combma- EXAMPLE 8 tion of formaldehyde and methylolmelamine low grade 1 condensation product is clearly recognized in data of crease-resistance after steaming. Silks own gloss is reduced only to a very slight degree through steaming.

EXAMPLE 7 Secured milk twill Habutai was dipped in a solution containing trimethylolmelamine-low grade condensation product (trademark Sumitex Resin M-3, made by Surnitomo Chemical, Japan), magnesium chloride catalyst (trademark Sumitex Accelerator MK, made by Sumitomo Chemical, Japan), and thiourea and then squeezed to a pick up of 200%. Thereafter, it was dried and treated with gaseous formaldehyde in the same man ner as that described in Example 7. Then, the fabric was subjected to soaping at a temperature of 50 C. for three min. with aqueous solution containing 0.2% of nonionic surface active agent (trademark Scourol 450, made by Kao Sekken, Japan) and thereafter, Washed and dried.

Crease resistance and hand-feeling of the fabric are gaseous formaldehyde for 2 hours which was evolved by given in Table 11.

TABLE 11 Sumitex Pick up of Accclthe resin Crease resistance after Crease resistance after erator after finishing (percent) soaping (percent) Sumitex Resin Thiourea finishing Hand-feeling M-3 (percent) (percent) (percent) (percent) RH 65% RH 95% RH 65% RH 95% after soaping 1.0 0.3 2. 80.1 75.8 78.3 68.8 Good. 2. 5 0.5 5. 7 85.0 81. 3 83. 8 80. 1 Do. 5. 0 1. 0 11.3 87. 3 84.0 85. 7v 82. 4 Do. 10.0 3.0 20.7 91.8 87.4 88.9 85.8 Do. 10. 0 4. 0 24. 5 91. 4 86.0 87. 3 85.1 Do. 10.0 5.0 29.0 89.3 80.4 86.9 75.8 Somewhat hard. 10. 0 7.0 34. 1 87. 7 78.8 86.0 73.0 Coarse and hard. Untreated fabric 76.7 41.5 75.8 42.0 Good.

heating paraformaldehyde stuffed at the bottom portion EXAMPLE 9 of the test tube, at a temperature of 120 C.

The resultant fabric was dyed at a temperature of 90 C. for min. in a bath containing 3% OWF of Kayanol Milling Red PG (trademark; made by Nihon Kayaku, Japan), 1% OWF of acetic acid and 30% OWF of anhydrous sodium sulfate; a bath ratio was 1: 100.

Crease resistance and other properties of-the fabric'are given in Table 10.

Scoured silk Habutai was dipped in a'solution containing 3% by weight of 'trimethylolmelamine-low grade resin (trade mark U-ramine T-10l, made by Mitsui-Toatsu Chemical, Japan), 3% of zinc nitrate catalyst (trademark Catalyst Z, made by Mitsui-Toatsu Chemical, Japan) and 10% of urea, squeezed with the same mangle as that of Example 6 to a pick up of 180% and then TABLE 10 Crease resistance Crease resistance 7 before dyeing Handafter dyeing Hand- (percent) cling (percent feeling Tear before after strength N0. RH RH 95% dyeing RH 65% RH 95% dyeing (g) 1 92. 1 87. 8 Good--..- 86. 6 2, 750 2 90.5 84.6 do 90.2 2,600

4 85.5 89 7 0-- 86.5 2,350 5 L... 72.3 48.3 ..-do 70.3 2,250 s l Untreated fabric;

Formaldehyde-low grade condensational resins and catalysts, which were used in this example, were as follows:

No. Formaldehyde low grade resin Catalyst 1 Sumitex Risen M-fi Sumitex Accelerator KX. 2 U-ramine T-33 Catalyst P? 3 U-ramine T-101. Do.

4 U-ramine T201 Do.

l Trademark; made by Mitsui-Toatsu Chemical, Japan. 1 Trademark; made by Mitsui-Toatsu Chemical, Japan.

d whiteness of the fabric are given TABLE 12 Pick up of the resin Crease resistance after Crease resistance after after finishing (percent) soaping (percent) Reaction Pressure at the beginning finishing whiteness temp. C) oi reaction (percent) RH 65% RH 95% RH 65% RH 96% (percent) 80 Atrn. pressure..- 15.8 80.3 72.1 78.5 68.9 98.9 100 do 18. 9 87.5 83. 8 83. 1 82. 4 98. 1 120 do 23.5 92.0 87.5 91.1 85.2 95.4 120 Reduced pressure (740 mm. Hg.)..- 20. 7 91.4 88.3 91.6 891 97. 8 140 do 21.8 90. 7 89. 4 91. 5 85. 4 88. 7 160 (in 21.5 91. 3 87. 5 91. 7 83.1 79. 180 do 22. 4 89. 5 88. 2 88. 9 85.9 75. 6 Untreated fabric 78. 4 42. 5 76. 5 41. 8 100 EXAMPLE 10 Secured Fuji silk was dipped in a solution containing 3% of trimeth lolmelamine-low rad resin it Y g 6 (Sum ex EXAMPLE 12 Resin M-S), 3% of zinc nitrate catalyst (Sumitex Accelerator KX) and 10% of thiourea. After dipping twice and nipping twice, the fabrics were squeezed with a mangle to a pick up of 200% and then dried under various conditions so that they had various moisture contents. The fabrics were treated with gaseous formaldehyde and then subjected to soaping, both being eifected under the same conditions as those described in Example 8. Results are given in Table 13.

5 dipped in a solution containing ethylene glycol or glyccrime and catalyst at room temperature for 5 min. After the dipped fabrics were squeezed to a pick up of 100%,

TABLE 13 Moisture Crease resistance Grease resistance content Pick up after finishing after soaping of the of the (percent) (percent) Drying fabric resin Hand-feeling conditions (percent) (percent) RH RH RH 65% RH 95% after soapiug C. x 10min. 3. 2 20.7 89.4 85. 5 87.4 83.3 Good. 100 C. x 5 min- 6. 8 21.1 89.3 86.1 86. 7 84.1 Do.- 100 C. x 3 min- 9. 7 22.0 90. 0 86. 5 85. 9 84. 7 Do. 80 C. x 10 min- 14. 7 25. 9 83. 5 77. 4 78. 4 72. 1 Somewhat hard. Air dried 10 min- 21.0 28.3 77.3 70.0 73. 3 66. 4 ar Air dried 15 min" 34. 5 30. 5 73. 6 66. 6 69. 9 63.0 Coarse and hard.

Untreated fabric 74. 3 42. 0 74.. 0 41. 8 00d.

EXAMPLE 1 1 5 0 they were dried with hot air until the moisture content descreased to 8% and thereafter, treated with gaseous formaldehyde at a temperature of C. for 3 hours, which was evolved by heating paraformaldehyde. Then, the fabrics were subjected to soaping using an aqueous solution containing 0.5% of nonionic surface active agent (trademark Scourol, made by Kao Sekken, Japan) and then washed and dried. Crease resistance and fading of the resultant fabrics are given in Table 15.

to that of Example 8. Results are given in Table 14. 0

TABLE 14 Pick up of the Crease resistance Crease resistance resin after after finishing after soaping Reaction finishing whiteness period On.) (percent) RH 65% RH 95% RH 65% RH 95% (percent) TABLE 15 Crease resistance (percent) Specimen Pro-treating bath RH RH RH fabrics composition (percent) 65% 85% 95% Wet Silk Habutai: Eth 1 1 1 8 y 6 g 37 y 1 nitrate }s1.5 87.0 86.2 83.

ycerine, 233 322 313;. .-.-I6611ehibhiifiii1bd .....I 85.0 75.0 68:2 68:2

Ethylene glycol 8 G 7 }ss.0 87.2 86.0 83.4

ycerine, 6 "{Mg chloride, 1 76.0 61.0 .0 3. 8 Thiourea treatment 88.0 87,0 86.5 86.0

After laundering at home Crease Shrinkage resistance percentage (percent) Fading (percent) D Laundering times ye Specimen fabrics stnif 10 20 10 20 20 Silk Habutai: A 82 6 80 8 5 4 1 Conventional method: The conventional method designates a method wherein methylol acrylamide and stannic chloride are used together. It has been reported that the method produces somewhat better results as wash-and-wear finishing than those by other conventional methods. The method is as follows: Fuji silk was dipped in a solution containing of commercially available U-ramine T-80. (Mitsui-Toatsu Chemical, Japan), 10% of stannic chloride and 1.5% of zinc nitrate for a period of 30 min. and then squeezed to a pick up of 100%. Therefater, the fabric was dried t a temperature of 70 C. for 6 min. and then cured at a temperature of 115 C. for 5 min. It was then soaped, rinsed and dried. The above method is hereinafter referred to as conventional method.

1 Tniourea-treating method: The method was as follows: Silk Habutai was dipped in a solution contaimng 10% thiourea and 3% catalyst (2- amino-2-methylpro anol salt ACX." made by Sumitomo Chemical, Japan) for a perio of 30 111111. and then squeezed to a pick up of 30%. After the fabric was dried until the moisture content reached less than 5%, it was treated with gaseous formaldehyde at a temperature of 120 C. for 3 hours which was evolved by heating paraformaldehyde and then soaped, rinsed and dried. The above method is hereinafter referred to as thiourea-treating method.

I Dyestuff: A=E1io Fast Red 2G8; B=Erio Acid Red XB. Scoured fabrics were dyed in a bath containing 2% OWF of dyes and thereafter, treated by the method of the present invention.

4 Shrinkage percentage: Shrinkage percentage is defined by the followmg equation: A1 th ft 1 d t eng a or aun enng imes Shrinkage percentage (percent) An mginal length wherein the shrinkage percentage is an average value of both shrinkage percentage in the warp and the filling directions.

As apparent from Table 15, the fabric which has been treated by the conventional method exhibits low crease resistance in all relative humidities of 6 5%, and On the other hand, the fabric which has been treated by the method of the present invention has remarkably high crease resistance being nearly equal to that of a commercially available wash-and-wcar finished polyester/cotton blended shirt nd accordingly, does not crease at the time of wearing.

Further, the fabric of the present invention exhibits higher Wet crease resistance and higher wet crease resistance after laundering at home 10 times and 20utimes, both resistances being nearly equal to that of the above polyester/cotton blended shirt, than that of the conventional method. As to fading, the fabric having been treated by the method of the present invention has been remarkably improved as compared with untreated Habntai or Fuji silk. As the fabric exhibits extremely low fading even after the repeated laundering of 10 or 20 times, which is the reverse of the fabric treated by the conventional method, it is not too much to say that the method of the present invention has actualized the washand-wear finish of silk fabrics.

Physical properties of the treated fabric are given in Table 16 in comparison with those of the untreated fabric.

EXAMPLE 13 Dyed silk Habutai was dipped in a solution containing aliphatic hydroxy compound, thiourca, urea and catalyst at room temperature for 5 min. and then squeezed to a pick up of After the fabric was dried with hot air until the moisture content reached 6% it was treated with gaseous formaldehyde at a temperature of C. for 3 hours which was evolved by heating paraformaldchyde and thereafter, soapcd, rinsed and dried.

Crease resistance and other properties of the resultant fabric are given in Table 17.

TABLE 17 After laundering at home Crease Shrinkage resistance percentage Crease resistance (percent) Fading (percent) (percent) Laundering times Preheating bath composition, RH RH RH Dyepercent 65% 85% 95% Wet stufis 1O 20 10 20 20 Ethylene glycol, 7 A 5 4 1 Thourea,3 88.0 87.0 86.5 83.0 B 82.0 81.0 6 4 0 Zn nitrate, 1- Mannitol, 8-- A 5 4 2 Thiourea,7 [87.5 86.0 83.4 82.5 B }81.9 801 5 4 0 i t%1 l' 1 1 rme yenegyco a .{Thiourea,5 }s9.0 86.5 84.0 82.0 }s1.e 805 g 2 0 Izgrhniltrate,ll

y y 4 .{Urea,5 -}ss.0 86.2 832 81.5{% 80.9 79.5 g i Zn nitrate, a Untreated 70.0 54.0 40.0 44.0 I i 4.0 0 Conventionalmcthod 85.0 75.0 110.2 08.2{% }00.0 00.1

EXAMPLE 14 EXAMPLE '17 Dyed silk Habutai was dipped in a solution containing Scoured silk Habutai was dipped in an aqueous solution aliphatic amine, thiourea and catalyst at room temperacontaining of one of aliphatic hydroxy compounds ture for 5 min. and then squeezed to a pick up of 100%. having various molecular weight, of thiourea and 3% After the fabric was dried until the moisture content 5 of zinc nitrate catalyst at a temperature of 50 C. for 5 reached less than 7%, it was treated with gaseous formalmin. and then squeezed with a angle to a pick up of dehyde in the same manner as that of Example 13. Re- 100%. sults are given in Table 18.

TABLE 18 Aiter laundering at home Crease Shrinkage resistance percentage Crease resistance (percent) Fading (percent) (percent) Laundering times Pretreating bath RH RH RH Dyecomposition, percent 65% 85% 95% Wet stufis 10 10 20 20 Ethanoiamine, 3- A 5 4 1---- Thiourea,7 85.2 83.0 82.2 B 5 4 0 0 31118 y EH6 2 .{Thiourea, 7.--. 84.5 82.8 81.5 F: g i} 0 Zn nitrate, 1-.. 3...- Untreated 79.0 54.0 46.0 44.0 {g i i 4.0 4--.- Conventionalmethod 85.0 75.0 68.2 68.2%} 3 EXAMPLE 15 Dyed silk Habutai was dipped in a solution containing aromatic hydroxy compound, thiourea and catalyst (trademark Sumitex Accelerator ACX, made by Sumitomo Chemical, Japan) at room temperature for 5 min. and then squeezed to a pick up of 100%. After the fabric was dried until the moisture content reached less than 8%, it was treated with gaseous formaldehyde in the same manner as that of Example 13. Results are given in Table 19.

After the fabric was dried with hot air until the moisture content reached to 68%, it was treated by the same method as that of Example 13. Results are given in Table 21. Molecular weight of polyethylene glycol was designated as average molecular weight in the table.

TABLE 19 After laundering at home Crease Shrinkage resistance percentage Crease resistance (percent) Fading (percent) Laundering times Pretreating bath RH RH RH Dyecomposition, percent 65% 85% 95% Wet stufis 10 20 10 2O 20 1.... Ice, 85.6 83.1

2,4-dihlsadroxy benzoic acid, 3

cx,s I 2,4-dihydroxy 2 .{Thiourea,5 84.0 82.5

5.--. Conventional method EXAMPLE 16 TABLE 21 After scoured silk Habutai was dipped in a solution Crease resistance containing aliphatic hydroxy compound, monoethanol Pretreatins solutwn (p amine and 3% of catalyst Sumitex Accelerator ACX) at Aliphatic hydmxy RH RH RH Hand. room temperature for 5 min, the fabric was treated by compound 5% t f i the same method as that of Example 15. Results are given 1 1 1 1 1 200 Egg 3 g 252 2%? i j 0 yet y eneg yco 7. o. m Table 3 --do 39.5 87.8 85.1 81.8 Do.

TABLE 20 65 4 do 500 ass 81.1 76.4 74.0 st me hat ar Crease resistance 83.0 77.8 78.3 72.6 Hard. Pretreatingbath composition (percent) (percent) 78.5 54.8 42.0 44.0 Good.

A] h h d g i Thi RH RH RH ip atic y roxy et ano 0- compound amine urea 65% 85% 95% Wet EXAMPLE 18 fitgggg ff g 321% 23;; 29:2 Scoured Fuji silk was dipped in a solution containing 31-- Mannito1,5 p 85. 3 82. 9 81. 3 ethylene glycol and thiourea, both being at varied concen- 1: o lg i n e gfl fflIIlI 32 3 23:2 25;; trations, and catalyst at room temperature for 5 min. and g MannitoLfi. gig-g 23.8 22-3 then treated by the same method as that of Example 17.

Results are given in Table 22.

TABLE 22 Pretreating solution Crease resistance composition (percent) H k (percent) Ethylene Zn up of RH TH RH glycol Thiourea nitrate resin 65% 85% Wet Hand-feeling.

1-.-- 1.0 1.0 0.3 3.2 85.0 81.6 78.4 79.3 Good. 2 2.0 2.5 0.5 6.5 87.0 84.7 81.8 81.0 Do; 3--.. 3.0 5.0 1.0 12.0 88.7 85.0 83.5 80.9 D0. 4.-.. 5.0 10.0 3.0 20.5 88.4 85.4 83.3 81.5 D0. 7.0 10.0 4.0 24.8 88.4 86.3 81.7 80.4 Do. 6.-.- 10.0 10.0 5.0 30.4 85.3 83.0 76.5 79.5 Somewhat hard; 7.-.- 15.0 10.0 6.0 38.7 85.1 81.7 73.4 78.0 Har 8 79.8 55.7 43.0 45.4 Good.

EXAMPLE 19 resultant fabric was finished by the conventional method scoured Fuji Silks were dipped in a Solution containing usually applied to wool fabrics. Results are given in 5% of ethylene glycol, 10% of thiourea and 3% of zinc Table TABLE 24 After laundering at home times Crease resistance (percent) Wet crease Shrinkage RH RH RH resistance percentage Dye- Fad- 65% 85% 95% Wet (percent) (percent) stufis ing Untreated 85.4 78.5 65.0 60.2 60.2 6.8 g 1 I A 4 Treated 90.1 89.1 87.1 80.0 80.0 2.0 B 4 nitrate catalyst at room temperature for 5 min. and then EXAMPLE 21 squeezed in the same manner as that of Example 17. After the fabric were dried under various conditions so that they had a moisture content different from each other, they were treated by the same method as that of Example 17. Results are given in Table 23.

TABLE 23 Crease resistance Moisture, Pick up (percent) Drying content of the conditions fabric resin RH RH RH C. x min.) (percent) (percent) 65% 85% 95% Wet Hand-feeling.

100 x 10 3. 8 20. 5 88. 5 86. 9 84. 0 80. 4 Good.

100 x 5 7. 2 21. 0 88. 3 87. 8 83. 6 79. 9 D0. 100 X 3 9. 8 21. 7 89.0 88. 1 83. 4 80. 7 D0. 4 80 x 10 15. 2 24. 8 82. 7 79. 0 73. 4 80. 3 Somewhat hard. 5 20 x 20 20. 8 27. 9 78. 4 75. 3 70. 5 79. 5 ar 6 20 x 15 33. 0 33. 4 74. 9 70. 4 69. 5 79. 6 Coarse and hard. 7 12. 8 0 77. 0 56. 4 42. 9 46. 3 Good.

EXAMPLE 20 1% of zinc mtrate catalyst at room temperature for 2 min.

and then squeezed to a pick up of 100% Immediately after the fabric was dried through a loop dryer until the moisture content reached less than 5% it was placed in a chamber filled with gaseous formaldehyde at a temperature of 160 C. which was produced from trioxane and ferric chloride and did not contain moisture. After 5 min., the fabric was taken out of the chamber and cooled. It was then soaped, washed and dried. Results are given in Table 25.

TABLE 25 Crease resistance (percent) After laundering at home 20 times Wet crease Shrinkage RH RH RH resistance percentage Dye- Fad- Wet (percent) (percent) stuffs ing Untreated--. 85.0 83.0 71.0 70.0 75.0 2.5 Treated as. 0 87.5 as. 5 e0. 0 s0. 0 0 {g 25 26 EXAMPLE 22 5. A method as claimed in claim 1, wherein said treat- Silk Hahn/[ah Which had been printed with a paste com ing of said fibrous structure with gaseous formaldehyde is taining 20 g./kg. of the same dyestuifs as tho of E effected under the conditions that a partial pressure of air ample 20, was dipped in a solution containing of tarsurrounding and existing inside said fibrous structure is taric acid, 7% of thourea and 3% of ACX for 5 min. and 5 less than 150 mm. Hg and both temperatures of said squeezed to a pick up of 100%. After the fabric was dried fib Structure d gaseous fqrmaldehyde a e more until the moisture content reached less than 5%, it was than the equilibrium condensation temperature corre treated with gaseous formaldehyde at a temperature of 110 C. which was evolved by heating paraformaldehyde. Spondmg to the partliular total Pressure After 3 hours, the fabric was soaped, rinsed and dried. 1O A method as 01211111611 111 c alm 5, wherein said gase- Results are given in Table 26. ous formaldehyde contains steam, the partial pressure of TABLE 26 After laundering at home times Crease resistance (percent) Wet crease Shrinkage RH RH RH resistance percentage Dye- Fad- 65% 85% 95% Wet (percent) (percent) stufis ing Uulieeletl 79.0 64.0 46.0 44.0 44.0 4 fig; Tte'd c-n 88.0 87.0 86.1 81. 2 80.0 o if} f What we claim is: which is no less than of the partial pressure of gase- 1. A method of finishing silk fibrous structure which ous formaldehyde. comprises treating said silk fibrous structure with a solu- R f e Cit d tion containing at least one member selected from the UNITED STATES PATENTS group consisting of (a) urea or thiourea, (b) a mixture of formaldehyde-containing low grade condensation resin and urea or thiourea, (c) aliphatic, alicylic or aromatic compounds having 2,434,247 1/1948 Lewls et at least two hydroxyl groups and having molecular 2,512,195 6/1950 Bener' weight of no more than 400, FOREIGN PATENTS (d) aliphatic amines having at least two groups se- 437,642 11/1935 Great Britain lected from hydroxyl and amino and having molecular Weight of no more than 400, OTHER REFERENCES drying the treated fibrous structure until the moisture con- G th i American Dyestuff Reporter, vol. 51, No. 14, tent of said fibrous structure reaches no more than 10% 31-3 l 9, 19 2 and then, treating Said fibrous Structure with gaseous 40 Gonzales et aL, American Dyestuif Reporter, Sept. 13, formaldehyde at a temperature of no less than C. 19 5, 74 and -19 2- A meth d as claimed in claim wherein said y- Mehta et al., Journal of the Textile Institute, vol. 58, ing is efiected until the moisture content of said fibrous 279-292 (1967) structure reaches no more than 7% 3. A method as claimed in claim 1, wherein said treat- 45 GEORGE F. LESMES, Primary Examiner ing of said fibrous structure with gaseous formaldehyde is effected at a temperature of no less than C. CANNON Asslstam Exammer 4. A method as claimed in claim 1, wherein said solu- U'S. CL tion further contains at least one catalyst for condensation polymerization. 50

2,123,152 7/1938 Rivat et a1. 2,143,352 1/1939 Koch et al. 2,311,080 2/ 1943 Pinkney. 

